Organic light emitting diode (OLED) display device is a new generation of display and has many advantages, such as self-illumination, rapid response speed, wide viewing angle, etc., in comparison with liquid crystal display, and thus can be used for flexible display, transparency display, 3D display, etc. Organic light emitting diode comprises an anode, a cathode and an organic functional layer. The main operation principle of the organic light emitting diode is that the current carriers driven by an electric field formed by the anode and the cathode are injected into the organic functional layer and complexed therein, thereby emitting light.
The cathode of the organic light emitting diode is typically made of a thin layer of metallic silver, and the anode is typically made of indium tin oxide (ITO). Both thin layer metallic silver and ITO have a high electrical resistivity. Especially for large area formed cathode, the cathode prepared from a thin layer of metallic silver has a relatively high electrical resistivity and a relatively high internal resistance drop (IR drop), resulting in a relatively great difference between the actual driving voltage of the OLED device and the supply voltage. Thus in a large-scale OLED display, there would be a large area with non-uniform lightness, and the display effect would be influenced.